FS-Cache: Add use of /proc and presentation of statistics

Make FS-Cache create its /proc interface and present various statistical
information through it.  Also provide the functions for updating this
information.

These features are enabled by:

	CONFIG_FSCACHE_PROC
	CONFIG_FSCACHE_STATS
	CONFIG_FSCACHE_HISTOGRAM

The /proc directory for FS-Cache is also exported so that caching modules can
add their own statistics there too.

The FS-Cache module is loadable at this point, and the statistics files can be
examined by userspace:

	cat /proc/fs/fscache/stats
	cat /proc/fs/fscache/histogram

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Daire Byrne <Daire.Byrne@framestore.com>

1 files changed, 212 insertions, 0 deletions

diff --git a/fs/fscache/stats.c b/fs/fscache/stats.c
new file mode 100644
index 00000000000..65deb99e756
--- /dev/null
+++ b/fs/fscache/stats.c
@@ -0,0 +1,212 @@
+/* FS-Cache statistics
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#define FSCACHE_DEBUG_LEVEL THREAD
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include "internal.h"
+
+/*
+ * operation counters
+ */
+atomic_t fscache_n_op_pend;
+atomic_t fscache_n_op_run;
+atomic_t fscache_n_op_enqueue;
+atomic_t fscache_n_op_requeue;
+atomic_t fscache_n_op_deferred_release;
+atomic_t fscache_n_op_release;
+atomic_t fscache_n_op_gc;
+
+atomic_t fscache_n_attr_changed;
+atomic_t fscache_n_attr_changed_ok;
+atomic_t fscache_n_attr_changed_nobufs;
+atomic_t fscache_n_attr_changed_nomem;
+atomic_t fscache_n_attr_changed_calls;
+
+atomic_t fscache_n_allocs;
+atomic_t fscache_n_allocs_ok;
+atomic_t fscache_n_allocs_wait;
+atomic_t fscache_n_allocs_nobufs;
+atomic_t fscache_n_alloc_ops;
+atomic_t fscache_n_alloc_op_waits;
+
+atomic_t fscache_n_retrievals;
+atomic_t fscache_n_retrievals_ok;
+atomic_t fscache_n_retrievals_wait;
+atomic_t fscache_n_retrievals_nodata;
+atomic_t fscache_n_retrievals_nobufs;
+atomic_t fscache_n_retrievals_intr;
+atomic_t fscache_n_retrievals_nomem;
+atomic_t fscache_n_retrieval_ops;
+atomic_t fscache_n_retrieval_op_waits;
+
+atomic_t fscache_n_stores;
+atomic_t fscache_n_stores_ok;
+atomic_t fscache_n_stores_again;
+atomic_t fscache_n_stores_nobufs;
+atomic_t fscache_n_stores_oom;
+atomic_t fscache_n_store_ops;
+atomic_t fscache_n_store_calls;
+
+atomic_t fscache_n_marks;
+atomic_t fscache_n_uncaches;
+
+atomic_t fscache_n_acquires;
+atomic_t fscache_n_acquires_null;
+atomic_t fscache_n_acquires_no_cache;
+atomic_t fscache_n_acquires_ok;
+atomic_t fscache_n_acquires_nobufs;
+atomic_t fscache_n_acquires_oom;
+
+atomic_t fscache_n_updates;
+atomic_t fscache_n_updates_null;
+atomic_t fscache_n_updates_run;
+
+atomic_t fscache_n_relinquishes;
+atomic_t fscache_n_relinquishes_null;
+atomic_t fscache_n_relinquishes_waitcrt;
+
+atomic_t fscache_n_cookie_index;
+atomic_t fscache_n_cookie_data;
+atomic_t fscache_n_cookie_special;
+
+atomic_t fscache_n_object_alloc;
+atomic_t fscache_n_object_no_alloc;
+atomic_t fscache_n_object_lookups;
+atomic_t fscache_n_object_lookups_negative;
+atomic_t fscache_n_object_lookups_positive;
+atomic_t fscache_n_object_created;
+atomic_t fscache_n_object_avail;
+atomic_t fscache_n_object_dead;
+
+atomic_t fscache_n_checkaux_none;
+atomic_t fscache_n_checkaux_okay;
+atomic_t fscache_n_checkaux_update;
+atomic_t fscache_n_checkaux_obsolete;
+
+/*
+ * display the general statistics
+ */
+static int fscache_stats_show(struct seq_file *m, void *v)
+{
+	seq_puts(m, "FS-Cache statistics\n");
+
+	seq_printf(m, "Cookies: idx=%u dat=%u spc=%u\n",
+		   atomic_read(&fscache_n_cookie_index),
+		   atomic_read(&fscache_n_cookie_data),
+		   atomic_read(&fscache_n_cookie_special));
+
+	seq_printf(m, "Objects: alc=%u nal=%u avl=%u ded=%u\n",
+		   atomic_read(&fscache_n_object_alloc),
+		   atomic_read(&fscache_n_object_no_alloc),
+		   atomic_read(&fscache_n_object_avail),
+		   atomic_read(&fscache_n_object_dead));
+	seq_printf(m, "ChkAux : non=%u ok=%u upd=%u obs=%u\n",
+		   atomic_read(&fscache_n_checkaux_none),
+		   atomic_read(&fscache_n_checkaux_okay),
+		   atomic_read(&fscache_n_checkaux_update),
+		   atomic_read(&fscache_n_checkaux_obsolete));
+
+	seq_printf(m, "Pages  : mrk=%u unc=%u\n",
+		   atomic_read(&fscache_n_marks),
+		   atomic_read(&fscache_n_uncaches));
+
+	seq_printf(m, "Acquire: n=%u nul=%u noc=%u ok=%u nbf=%u"
+		   " oom=%u\n",
+		   atomic_read(&fscache_n_acquires),
+		   atomic_read(&fscache_n_acquires_null),
+		   atomic_read(&fscache_n_acquires_no_cache),
+		   atomic_read(&fscache_n_acquires_ok),
+		   atomic_read(&fscache_n_acquires_nobufs),
+		   atomic_read(&fscache_n_acquires_oom));
+
+	seq_printf(m, "Lookups: n=%u neg=%u pos=%u crt=%u\n",
+		   atomic_read(&fscache_n_object_lookups),
+		   atomic_read(&fscache_n_object_lookups_negative),
+		   atomic_read(&fscache_n_object_lookups_positive),
+		   atomic_read(&fscache_n_object_created));
+
+	seq_printf(m, "Updates: n=%u nul=%u run=%u\n",
+		   atomic_read(&fscache_n_updates),
+		   atomic_read(&fscache_n_updates_null),
+		   atomic_read(&fscache_n_updates_run));
+
+	seq_printf(m, "Relinqs: n=%u nul=%u wcr=%u\n",
+		   atomic_read(&fscache_n_relinquishes),
+		   atomic_read(&fscache_n_relinquishes_null),
+		   atomic_read(&fscache_n_relinquishes_waitcrt));
+
+	seq_printf(m, "AttrChg: n=%u ok=%u nbf=%u oom=%u run=%u\n",
+		   atomic_read(&fscache_n_attr_changed),
+		   atomic_read(&fscache_n_attr_changed_ok),
+		   atomic_read(&fscache_n_attr_changed_nobufs),
+		   atomic_read(&fscache_n_attr_changed_nomem),
+		   atomic_read(&fscache_n_attr_changed_calls));
+
+	seq_printf(m, "Allocs : n=%u ok=%u wt=%u nbf=%u\n",
+		   atomic_read(&fscache_n_allocs),
+		   atomic_read(&fscache_n_allocs_ok),
+		   atomic_read(&fscache_n_allocs_wait),
+		   atomic_read(&fscache_n_allocs_nobufs));
+	seq_printf(m, "Allocs : ops=%u owt=%u\n",
+		   atomic_read(&fscache_n_alloc_ops),
+		   atomic_read(&fscache_n_alloc_op_waits));
+
+	seq_printf(m, "Retrvls: n=%u ok=%u wt=%u nod=%u nbf=%u"
+		   " int=%u oom=%u\n",
+		   atomic_read(&fscache_n_retrievals),
+		   atomic_read(&fscache_n_retrievals_ok),
+		   atomic_read(&fscache_n_retrievals_wait),
+		   atomic_read(&fscache_n_retrievals_nodata),
+		   atomic_read(&fscache_n_retrievals_nobufs),
+		   atomic_read(&fscache_n_retrievals_intr),
+		   atomic_read(&fscache_n_retrievals_nomem));
+	seq_printf(m, "Retrvls: ops=%u owt=%u\n",
+		   atomic_read(&fscache_n_retrieval_ops),
+		   atomic_read(&fscache_n_retrieval_op_waits));
+
+	seq_printf(m, "Stores : n=%u ok=%u agn=%u nbf=%u oom=%u\n",
+		   atomic_read(&fscache_n_stores),
+		   atomic_read(&fscache_n_stores_ok),
+		   atomic_read(&fscache_n_stores_again),
+		   atomic_read(&fscache_n_stores_nobufs),
+		   atomic_read(&fscache_n_stores_oom));
+	seq_printf(m, "Stores : ops=%u run=%u\n",
+		   atomic_read(&fscache_n_store_ops),
+		   atomic_read(&fscache_n_store_calls));
+
+	seq_printf(m, "Ops    : pend=%u run=%u enq=%u\n",
+		   atomic_read(&fscache_n_op_pend),
+		   atomic_read(&fscache_n_op_run),
+		   atomic_read(&fscache_n_op_enqueue));
+	seq_printf(m, "Ops    : dfr=%u rel=%u gc=%u\n",
+		   atomic_read(&fscache_n_op_deferred_release),
+		   atomic_read(&fscache_n_op_release),
+		   atomic_read(&fscache_n_op_gc));
+	return 0;
+}
+
+/*
+ * open "/proc/fs/fscache/stats" allowing provision of a statistical summary
+ */
+static int fscache_stats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, fscache_stats_show, NULL);
+}
+
+const struct file_operations fscache_stats_fops = {
+	.owner		= THIS_MODULE,
+	.open		= fscache_stats_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};